Presently, so-called hard coating materials are the mainstream of ultraviolet curable seal materials. Raw materials of such hard coating materials are ordinarily compositions having a main component of bisphenol A type epoxy (meth)acrylate. Such compositions are excellent in gas/water vapor barrier property (hereinafter, water vapor barrier property is referred to as merely “barrier property” if without special definition), while on the other hand, the cured products thereof are extremely hard. Therefore, such compositions are unusable in cases that softness or flexibility is required. Materials for use in seal materials required for softness include, for example, a material which has a probability of being bended, such as a sealer or packing relating to flexible display and the like, or members used in a high-compressed condition, such as a gasket for hard disc drive (hereinafter referred to as “HDD”) and the like (for example, JP2010-260918A and JP2009-43295A (PTL 1 and PTL 2)).
On the other hand, ultraviolet curable materials having softness (hereinafter referred to as “ultraviolet curable elastomer” in order to clearly distinguish from ultraviolet curable materials without softness) include polyester acrylate, urethane acrylate, etc. (For example, see PTL 1 and PTL 2.)